An important for goal for agriculture is to produce plants with beneficial agronomic traits. Recent advances in genetic manipulation provide the tools to transform plants with polynucleotide sequences of interest and to express such sequences within the transformed plants. This has led to the development of plants capable of expressing pharmaceuticals and other chemicals, plants with increased pest resistance, increased stress tolerance and many other beneficial traits.
It is often desirable to control expression of a polynucleotide of interest, in a particular tissue, at a particular developmental stage, or under particular conditions, in which the polynucleotide is not normally expressed. The polynucleotide of interest may encode a protein or alternatively may be intended to effect silencing of a corresponding target gene.
Plant promoter sequences are useful in genetic manipulation for directing expression of polynucleotides in transgenic plants. To achieve this, a genetic construct is often introduced into a plant cell or plant. Typically such constructs include a plant promoter operably linked to the polynucleotide sequence of interest. Such a promoter need not normally be associated with the gene of interest. Once transformed, the promoter controls expression of the operably linked polynucleotide of interest thus leading to the desired transgene expression and resulting desired phenotypic characteristics in the plant.
Promoters used in genetic manipulation are typically derived from the 5′ un-transcribed region of genes and contain regulatory elements that are necessary to control expression of the operably linked polynucleotide. Promoters useful for plant biotechnology can be classified depending on when and where they direct expression. For example promoters may be tissue specific or constitutive (capable of transcribing sequences in multiple tissues). Other classes of promoters include inducible promoters that can be triggered by external stimuli such as environmental and chemical stimuli.
Often a relatively high level of expression of the transformed sequence of interest is desirable. This is often achieved through use of viral promoter sequences such as the Cauliflower Mosaic Virus 35S promoter. In some circumstances it may be more preferable to use a plant derived promoter rather than a promoter derived from a microorganism. It may also be preferable in some circumstances to use a promoter derived from, or produced from sequences derived from, the species to be transformed.
It would be beneficial to have a variety of promoters available in order to ensure that transgenes are transcribed at an appropriate level in the right tissues, and at an appropriate stage of growth or development.
The apple (Malus species) is a major fruit species grown in New Zealand and other temperate climates throughout the world. Valuable traits that may be improved by genetic manipulation of apple include: fruit flavour, fruit colour, content of health promoting components (such as anthocyanins and flavanoids) in fruit, stress tolerance/resistance, pest tolerance/resistance and disease tolerance/resistance.
Genetic manipulation of such traits in apple, and these and other traits in other species, is limited by the availability of promoters capable of appropriately controlling the expression of genes of interest.
It is therefore an object of the present invention to provide a promoter useful for controlling gene expression in apple and other plants and/or at least to provide a useful choice.